Automatic fire-alarm



(No Model.)

W. A. GUTHRIE. AUTOMATIC FIRE ALARM. No. 530,839.

Patented Dec. 11,1894.

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WITNESSES Way ZbT (j/giZR Jy m,

' Attorney UNITED STATES PATENT OFFICE.

WILLIAM A. GUTHRIE, OF DURHAM, NORTH CAROLINA.

AUTOMATIC FIRE-ALARM.

SPECIFICATION-forming part of Letters Patent No. 530,839, dated December 11, 1894.

Application filed April 26, 1894. Serial No. 509,120. (No model.)

T0 61% whom it may concern..-

Be it known that I, WILLIAM A. GUTHRIE, a citizen of the United States, and a resident of Durham, in the county of Durham and State of North Carolina, have invented certain new and useful Improvements in Automatic Fire- Alarms; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification.

Figure l of the drawings is a diagrammatic view of the invention. Fig. 2 is an elevation of the circuit closing device, the solder being fused and weight fallen. Fig. 3 is a detail of the metallic link.

This invention has relation to certain new and useful improvements in automatic fire alarms, and is more especially designed as an improvement upon the alarm set forth and claimed in my Patent No. 514,361, dated February 6, 1894.

The invention more particularly consists in an improved thermostat or automatic circuit closing device, the object being to simplify the construction of this device, and also to provide means for insuring a more perfect and reliable contact, all as hereinafter described and pointed out in the appended claims.

Referring to the accompanying drawings, the letter A indicates a battery; 13, an electric bell or alarm, of any suitable character, and O, my improved automatic circuit-closing device, all connected in an electric circuit D. Said circuit-closing device comprises a base of hard rubber, or other good insulating material, and provided with holes therethrough by means of which it may be readily secured either to the ceiling of a room or apartment, or in such other position therein as may be most desirable. Secured to said base near one end thereof is a spring arm E of steel, or other material which is a' good conductor of electricity. Secured to the opposite portion of the base is a contact plate F, one end pertion of which is overlapped a short distance by the free portion of said arm. At a said plate is provided with a contact point, preferably of platinum, and directly opposite a corresponding point I) on said spring arm. On the underside of said spring arm, near its free end, is a small perforated lug c, from which is suspended a weight G sufficiently heavy to overcome the tension of the arm and hold the two points a and I) out of contact. Said weight preferably consists of a ball, having an eyed, and the connection between said ball and the spring arm consists of a metallic link H, formed in two sections, each of which is provided with a hook h, one of said hooks being adapted to engage the eye of the lug o and the other the eye of the weight. The two sections of this link are joined to each other by means of a solder which consists of an alloy which fuses at a low temperature, such as alloys of tin, lead and bismuth, or tin, lead, bismuth and cadmium, whose fusing point is considerably below the temperature of boiling water.

K designates a back stop for the spring arm E, which prevents the weight from pulling the arm downwardly so far as to strain it or destroy its tension, it being necessary in some instances to use a weight of considerable magnitude, as will be seen by reference to my Patent No. 514,362, of February 6, 1894, wherein the weight assists in operating a valve lever. Said stop preferably consists of a bent arm secured to the base, and having at its bent extremity, underneath the free end of the arm, a contact lug 7c of insulating material.

The circuit wires are led through holes in the base and are connected respectively by binding posts or screws p p with the arm E and plate F.

Upon undue rise of temperature in the room or apartment in which the circuit-closer is situated, the fusible solder melts, releasing the weight, and the arm E makes contact with the plate F, completing the circuit, and sounding the alarm.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is-

1. In an automatic fire alarm, the combination with an electrical circuit, including a source and an alarm, of an automatic closing device for such circuit, and forming a part thereof, said'device comprising an insulated base, a spring conducting arm E secured thereto and connected with one terminal of the circuit, a contact plate also secured to said base, and connected with the other terminal of the circuit,aweight suspended from the free portion of said arm E and normally holding it out of contact with said plate, a two-part metallic hook connecting said spring and Weight, a fusible alloy connecting the two parts of said hook, and a back stop for said spring arm, whereof the weight is prevented from straining said arm, substantially as specified. 2. The herein described automatic circuit closer for fire alarms, comprising a non-conducting base, a spring arm secured thereto, a contact plate also secured to said base, contact points on said arm and plate, a weight suspended from the free portion of said spring and normally holding it out of contact with said plate, a two part hooked-link forming the suspension medium, an easily fused metallic alloy forming the connection between the parts of said link, and a safety back stop arm for said spring arm, substantially as specified.

In testimony whereof I ailix my signature in presence of two witnesses.

WILLXAM A. GUTHRIE.

Witnesses:

L. A. CARR, E. G. SINEBERRY. 

